The present disclosure relates to transmitting apparatuses, transmitting methods, and programs and, more particularly, to a transmitting apparatus, a transmitting method, and a program that enable data to be transmitted with low delay regardless of a state of a data channel, e.g., a network.
In recent years, for example, remote surgery has been carried out in which a surgeon performs surgery on a patient by operating robotic arms from a remote location. In this remote surgery, since the surgeon operates the robotic arms while watching moving images obtained by capturing images of the surgery, the moving images are desirably transmitted with a low delay of several frames or less (substantially in real time).
In order to transmit (send) moving images or the like with a low delay of several frames or less via a data channel, such as the Internet, there has been proposed a coding technique for performing wavelet transform coding (compression) on each block of several lines of each picture that constitutes the moving images (see, for example, Japanese Unexamined Patent Application Publication No. 2007-311924).
With this coding technique, a transmitting apparatus can start encoding without waiting for input of the entire data of a picture and transmit the resulting encoded data. Also, a receiving apparatus can start decoding (decompression) before receiving the entire encoded data from the transmitting apparatus.
Accordingly, when congestion (traffic jam) is not caused in a network, delay due to the network congestion does not occur. As a result, the transmission time of the encoded data (time for the encoded data to reach the receiving apparatus from the transmitting apparatus via the network) becomes sufficiently short and, thus, the transmitting apparatus can transmit moving images with low delay.
However, when congestion is caused in the network, delay due to the network congestion occurs. As a result, the transmission time of the encoded data increases and, thus, the transmitting apparatus can no longer transmit moving images with low delay.
Accordingly, there is a rate control process for adjusting a transmission rate, which represents the amount of encoded data transmitted per unit time, in accordance with the congestion state of the network in order to sufficiently shorten the transmission time regardless of the congestion state of the network.
In this rate control process, the transmitting apparatus temporarily stores the encoded data in a transmission buffer thereof, thereby transmitting the encoded data to the receiving apparatus at the transmission rate adjusted by the rate control process.